Newly revised Section 10 for ES3.1.

[Maciej Stachowiak]

On Jul 9, 2008, at 5:16 PM, Allen Wirfs-Brock wrote:

>
> Const and function declarations within blocks must be uniquely  
> named, such a declaration may not over-write a preceding declaration  
> in the same block and an attempt to do so is a syntax error.  Such  
> declarations, of course, shadow any like named declarations in  
> enclosing scopes. Since consts and function declarations in blocks  
> are new, this is a new semantics.

Although the standard does not allow block-level function  
declarations, the following will parse and give identical results in  
all four of the major browsers (it will alert "2"):

<script>
function g() {
     if (true) {
         function f() { alert("1"); }
         function f() { alert("2"); }
     }
     f();
}
g();
</script>

This example will interoperably alert "1":

<script>
function g() {
     if (true) {
         function f() { alert("1"); }
     }
     f();
}
g();
</script>

As I understand it, your proposal would make the first example a  
syntax error and the second a runtime error (unless a global function  
named f is defined).

I know from experience that sites do accidentally depend on the  
intersection of the different IE and Firefox extensions for block- 
level function declarations (and the Safari and Opera attempts to  
emulate them). Do you have evidence that leads you to conclude that  
your proposed behavior is compatible with the Web? I am almost certain  
it is not.


Regards,
Maciej

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